Liz Gowen on sat 5 jan 02
After reading all the info on clayart regarding safe glazes I
decided to buy a liner glaze until I could make one to my liking for
pottery used for food. I had purchased 5 lb.of a translucent cone 6
glaze several years ago, I assume, from looking at a sample of
something glazed in a show room and decided to use some this year.
Looks great smooth on porcelain. Went back to make sure it was still
available and found out it was a LEADED glaze. This was pointed out
by the owner of my supply place. I am freaked to say the least.
Yes it is marked in the catalogue as leaded but I didn't order
it from the catalogue. I don't remember what I have used it on
though since the bag is pretty full and I only tried it a few months
ago I hope not too much. The few in my kitchen I have pulled from
the shelves. Have I now screwed up and contaminated my kiln for
other work? Where do I get rid of the rest of this glaze. How do I
remember what else I used it on!
I really think putting translucent 533 on a bag of leaded glaze
is not enough! For glazes with cadmium and lead I feel it should be
clearly marked on the bag contains lead. Perhaps this is my medical
background coming through but my memory just can't keep all these
numbers on its hard drive (Think I need another memory chip) but
seriously I don't think asking for better labeling or even a sticker
that says contains lead. is too much.
Frazzled
Liz Gowen NJ USA
John Hesselberth on sat 5 jan 02
on 1/5/02 1:34 PM, Liz Gowen at elgowen@HOME.COM wrote:
> Went back to make sure it was still
> available and found out it was a LEADED glaze. This was pointed out
> by the owner of my supply place. I am freaked to say the least.
> Yes it is marked in the catalogue as leaded but I didn't order
> it from the catalogue. I don't remember what I have used it on
> though since the bag is pretty full and I only tried it a few months
> ago I hope not too much. The few in my kitchen I have pulled from
> the shelves. Have I now screwed up and contaminated my kiln for
> other work? Where do I get rid of the rest of this glaze. How do I
> remember what else I used it on!
Hi Liz,
Your experience is certainly a concerning one, but hopefully not as bad as
you are now imagining. First there are food safe lead-containing glazes and
hopefully this is one--at least they are food-safe by FDA rules. If you are
really concerned you can have one of your pieces tested. That might give
you some piece of mind. You can find instructions for testing on my
frogpondpottery web site (full URL below).
Second you can easily check to see if you kiln is contaminated. Any decent
hardware store in the US and probably in many countries sells lead test
kits. They are designed to be used to test for lead paint or lead in
ceramic glazes. They won't give a quantitative number but they can be used
to tell if there is lead in your kiln or not. If there is you can probably
purge it by firing it empty a few times with your kiln ventilation system on
and the top lid cracked. Make sure your kiln room is totally ventilated
during this process also. Retest after each firing until you don't test
positive for lead using the hardware store kit.
As for getting rid of the rest of the glaze, most communities have a toxic
substance collection program every few months. Take it to one of those
spots and they should take it off your hands. You may also find a potter
who is still using lead glazes on decorative work and will take it off your
hands. There are fewer and fewer of those people, but they are still
around.
I agree with you that all lead containing glazes should be well labeled.
Hopefully some glaze suppliers on the list will see your message and take
action.
Good luck and don't panic. A few simple steps and you'll be fine.
Regards,
John
web sites: http://www.masteringglazes.com and http://www.frogpondpottery.com
EMail: john@frogpondpottery.com
"Pots, like other forms of art, are human expressions: pleasure, pain or
indifference before them depends upon their natures, and their natures are
inevitably projections of the minds of their creators." Bernard Leach, A
Potter's Book.
Jose A. Velez on sat 5 jan 02
Liz, you wrote:
>Went back to make sure it was still
> available and found out it was a LEADED glaze. This was pointed out
> by the owner of my supply place. I am freaked to say the least.
> Liz Gowen NJ USA
When buying dry chemicals to formulate glazes I have found the suppliers
never offer the MSDS (Material Safety Data Sheet), but if I ask they do
supply them. If you are not familiar with the MSDS, they are a short form
containing basic information on the safety and health hazards of the
material (toxicity, flamability, etc.). They can be rather technical, but
at least it gives you an idea of what you are dealing with and possible
mitigations. Suppliers are mandated by law to have these available. I have
obtained them for dry chemicals as well as stains. I do not know if they
are available for comercial glazes, but I suppose they should be. I
believe it is a good practice to ask for these every time you buy a material
you are not familiar with and keep them filed for future reference. This is
especially true if you have materials you do not use frequently.
I hope this might help in the future. As to how to get rid of the leaded
glaze there are organizations that hold chemicals collection and disposal
events, or you might be able to return it to your supplier. Another way
might be to fire in a clay form, so that it is encapsulated and then dispose
of the solid (although I have never done this I believe this is a practice
used by some potters).
Regards,
Jose A. Velez
>
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miriam shelomith on tue 8 jan 02
Have been following this conversation about leaded glazes with interest. I
was taught, 30+ years ago, that the danger of using lead was only found in
the low fire glazes. Doesn't it burn out and change it's chemical
composition by the time it reaches cone 6?
pottermim
>After reading all the info on clayart regarding safe glazes I decided to
>buy a liner glaze until I could make one to my liking for pottery used for
>food. I had purchased 5 lb.of a translucent cone 6 glaze several years ago,
>I assume, from looking at a sample of something glazed in a show room and
>decided to use some this year. Looks great smooth on porcelain. Went back
>to make sure it was still available and found out it was a LEADED glaze.
>This was pointed out by the owner of my supply place. I am freaked to say
>the least. Yes it is marked in the catalogue as leaded but I didn't order
>it from the catalogue. I don't remember what I have used it on though since
>the bag is pretty full and I only tried it a few months ago I hope not too
>much. The few in my kitchen I have pulled from the shelves. Have I now
>screwed up and contaminated my kiln for other work? Where do I get rid of
>the rest of this glaze. How do I remember what else I used it on! I really
>think putting translucent 533 on a bag of leaded glaze is not enough! For
>glazes with cadmium and lead I feel it should be clearly marked on the bag
>contains lead. Perhaps this is my medical background coming through but my
>memory just can't keep all these numbers on its hard drive (Think I need
>another memory chip) but seriously I don't think asking for better labeling
>or even a sticker that says contains lead. is too much. Frazzled Liz Gowen
>NJ USA
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Ron Roy on fri 11 jan 02
The law says it has to be labeled toxic I think - a good reason to ask for
a MSDS when ever you buy materials - Lead and Cadmium are not the only
toxic items we get mixed in with clay and glazes - manganese comes to mind
for one - a real hazard to potters.
RR
> After reading all the info on clayart regarding safe glazes I
>decided to buy a liner glaze until I could make one to my liking for
>pottery used for food. I had purchased 5 lb.of a translucent cone 6
>glaze several years ago, I assume, from looking at a sample of
>something glazed in a show room and decided to use some this year.
>Looks great smooth on porcelain. Went back to make sure it was still
>available and found out it was a LEADED glaze. This was pointed out
>by the owner of my supply place. I am freaked to say the least.
> Yes it is marked in the catalogue as leaded but I didn't order
>it from the catalogue. I don't remember what I have used it on
>though since the bag is pretty full and I only tried it a few months
>ago I hope not too much. The few in my kitchen I have pulled from
>the shelves. Have I now screwed up and contaminated my kiln for
>other work? Where do I get rid of the rest of this glaze. How do I
>remember what else I used it on!
> I really think putting translucent 533 on a bag of leaded glaze
>is not enough! For glazes with cadmium and lead I feel it should be
>clearly marked on the bag contains lead. Perhaps this is my medical
>background coming through but my memory just can't keep all these
>numbers on its hard drive (Think I need another memory chip) but
>seriously I don't think asking for better labeling or even a sticker
>that says contains lead. is too much.
> Frazzled
> Liz Gowen NJ USA
Ron Roy
RR# 4
15084 Little Lake Rd..
Brighton,
Ontario, Canada
KOK 1H0
Residence 613-475-9544
Studio 613-475-3715
Fax 613-475-3513
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